1. Field of the Invention
The present invention relates to a method for manufacturing a sheet-conveying roller that conveys sheets on which an image is formed, the sheet-conveying roller used in an image forming apparatus such as a laser beam printer. The present invention is also related to an image forming apparatus in which the sheet-conveying roller is used. More particularly, the present invention relates to a method of obtaining a sheet-conveying roller, the weight of which is small and the machining accuracy of which is high.
2. Description of the Related Art
As well known, for example, in an image forming apparatus such as a laser beam printers a feed motor for feeding sheets and an image forming means are operated according to control data and image forming data which are sent from a host computer such as a personal computer (PC), and the sheets supplied by a conveyance unit, which is arranged on the upstream side, are sent out at a predetermined pitch to a predetermined image forming position on a base frame of the image forming means, which is arranged on the downstream side, by a feed roller driven by the feed motor, and an image such as a predetermined character or figure is formed on the sheet at a predetermined image forming position by the image forming means. Accordingly, it is necessary for a sheet-conveying roller, especially for the feed roller to feed a sheet so that it cannot deviate from a predetermined feeding passage. Therefore, the feed roller is highly accurately machined for alignment so that the deviation cannot be caused. Further, it is necessary for the outer diameter of the feed roller to be formed uniform, that is, it is necessary for the dimensions of the feed roller to be maintained uniform. For the above reasons, it is common that the feed roller is made out of a solid round bar by means of cutting. However, this type of feed roller goes against a demand of reducing the weight of the apparatus.
From the above viewpoints, in order to reduce the weight, a roller is conventionally provided in which a shaft is press-fitted into a hollow portion of a pipe-shaped roller, and a circumferential face of a flange portion of the shaft and an inner face of the roller are bonded to each other or caulked to each other by a caulking machine (see JP-A-04-173365) Further, another roller is conventionally provided in which a shaft is engaged inside a cylindrical roller, and an end portion of the roller and the shaft are fixed to each other being welded by fillet welding (see JP-A-10-281140).